scholarly journals Response of Northern Hemisphere weather and climate to Arctic sea ice decline: Resolution independence in Polar Amplification Model Intercomparison Project (PAMIP) simulations

2021 ◽  
pp. 1-39
Author(s):  
Jan Streffing ◽  
Tido Semmler ◽  
Lorenzo Zampieri ◽  
Thomas Jung
Keyword(s):  
Sea Ice ◽  
Horizontal Resolution ◽  
Arctic Sea Ice ◽  
Model Intercomparison ◽  
Polar Amplification ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
Weather And Climate ◽  
Intercomparison Project ◽  
The Impact

AbstractThe impact of Arctic sea ice decline on the weather and climate in mid-latitudes is still much debated, with observation suggesting a strong and models a much weaker link. In this study, we use the atmospheric model OpenIFS, in a set of model experiments following the protocol outlined in the Polar Amplification Model Intercomparison Project (PAMIP), to investigate whether the simulated atmospheric response to future changes in Arctic sea ice fundamentally depends on model resolution. More specifically, we increase the horizontal resolution of the model from 125km to 39km with 91 vertical levels; in a second step resolution is further increased to 16km with 137 levels in the vertical. The model does produce a response to sea ice decline with a weaker mid latitude Atlantic jet and increased blocking in the high latitude Atlantic, but no sensitivity to resolution can be detected with 100 members. Furthermore we find that the ensemble convergence toward the mean is not impacted by the model resolutions considered here.

Response of Northern Hemisphere weather and climate to Arctic sea ice decline: The role of resolution in Polar Amplification Model Intercomparison Project (PAMIP) simulations

2021 ◽  
Author(s):  
Jan Streffing ◽  
Tido Semmler ◽  
Lorenzo Zampieri ◽  
Thomas Jung
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Atmospheric Response ◽  
Model Intercomparison ◽  
Polar Amplification ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
Weather And Climate ◽  
Intercomparison Project ◽  
The Mean

<p>The impact of Arctic sea ice decline on the weather and climate in mid-latitudes is still much debated, with observation suggesting a strong and models a much weaker link. In this study, we use the atmospheric model OpenIFS, in a set of model experiments following the protocol outlined in the Polar Amplification Model Intercomparison Project (PAMIP), to investigate whether the simulated atmospheric response to future changes in Arctic sea ice fundamentally depends on model resolution. More specifically, we increase the horizontal resolution of the model from 125km to 39km with 91 vertical levels; in a second step resolution is further increased to 16km with 137 levels in the vertical. We find that neither the mean atmospheric response nor the ensemble convergence toward the mean are strongly impacted by the model resolutions considered here.</p>

scholarly journals The Polar Amplification Model Intercomparison Project (PAMIP) contribution to CMIP6: investigating the causes and consequences of polar amplification

2018 ◽  
Author(s):  
Doug M. Smith ◽  
James A. Screen ◽  
Clara Deser ◽  
Judah Cohen ◽  
John C. Fyfe ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Sea Surface ◽  
Model Intercomparison ◽  
Physical Processes ◽  
Polar Amplification ◽  
Arctic Sea ◽  
Intercomparison Project

Abstract. Polar amplification – the phenomenon that external radiative forcing produces a larger change in surface temperature at high latitudes than the global average – is a key aspect of anthropogenic climate change, but its causes and consequences are not fully understood. The Polar Amplification Model Intercomparison Project (PAMIP) contribution to the Sixth Coupled Model Intercomparison Project (CMIP6, Eyring et al. 2016) seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments documented here. In particular, PAMIP will address the following primary questions: 1. What are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification? 2. How does the global climate system respond to changes in Arctic and Antarctic sea ice? These issues will be addressed with multi-model simulations that are forced with different combinations of sea ice and/or sea surface temperatures representing present day, pre-industrial and future conditions. The use of three time periods allows the signals of interest to be diagnosed in multiple ways. Lower priority tier experiments are proposed to investigate additional aspects and provide further understanding of the physical processes. These experiments will address the following specific questions: What role does ocean-atmosphere coupling play in the response to sea ice? How and why does the atmospheric response to Arctic sea ice depend on the pattern of sea ice forcing? How and why does the atmospheric response to Arctic sea ice depend on the model background state? What are the roles of local sea ice and remote sea surface temperature in polar amplification, and the response to sea ice, over the recent period since 1979? How does the response to sea ice evolve on decadal and longer timescales? A key goal of PAMIP is to determine the real world situation using imperfect climate models. Although the experiments proposed here form a coordinated set, we anticipate a large spread across models. However, this spread will be exploited by seeking emergent constraints in which model uncertainty may be reduced by using an observable quantity that physically explains the inter-model spread. In summary, PAMIP will improve our understanding of the physical processes that drive polar amplification and its global climate impacts, thereby reducing the uncertainties in future projections and predictions of climate change and variability.

scholarly journals The Polar Amplification Model Intercomparison Project (PAMIP) contribution to CMIP6: investigating the causes and consequences of polar amplification

2019 ◽  
Vol 12 (3) ◽  
pp. 1139-1164 ◽  
Author(s):  
Doug M. Smith ◽  
James A. Screen ◽  
Clara Deser ◽  
Judah Cohen ◽  
John C. Fyfe ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Sea Surface ◽  
Model Intercomparison ◽  
Physical Processes ◽  
Polar Amplification ◽  
Arctic Sea ◽  
Intercomparison Project

Abstract. Polar amplification – the phenomenon where external radiative forcing produces a larger change in surface temperature at high latitudes than the global average – is a key aspect of anthropogenic climate change, but its causes and consequences are not fully understood. The Polar Amplification Model Intercomparison Project (PAMIP) contribution to the sixth Coupled Model Intercomparison Project (CMIP6; Eyring et al., 2016) seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments documented here. In particular, PAMIP will address the following primary questions: (1) what are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification? (2) How does the global climate system respond to changes in Arctic and Antarctic sea ice? These issues will be addressed with multi-model simulations that are forced with different combinations of sea ice and/or sea surface temperatures representing present-day, pre-industrial and future conditions. The use of three time periods allows the signals of interest to be diagnosed in multiple ways. Lower-priority tier experiments are proposed to investigate additional aspects and provide further understanding of the physical processes. These experiments will address the following specific questions: what role does ocean–atmosphere coupling play in the response to sea ice? How and why does the atmospheric response to Arctic sea ice depend on the pattern of sea ice forcing? How and why does the atmospheric response to Arctic sea ice depend on the model background state? What have been the roles of local sea ice and remote sea surface temperature in polar amplification, and the response to sea ice, over the recent period since 1979? How does the response to sea ice evolve on decadal and longer timescales? A key goal of PAMIP is to determine the real-world situation using imperfect climate models. Although the experiments proposed here form a coordinated set, we anticipate a large spread across models. However, this spread will be exploited by seeking “emergent constraints” in which model uncertainty may be reduced by using an observable quantity that physically explains the intermodel spread. In summary, PAMIP will improve our understanding of the physical processes that drive polar amplification and its global climate impacts, thereby reducing the uncertainties in future projections and predictions of climate change and variability.

Observationally constrained multi-model atmospheric response to future Arctic sea ice loss 

2021 ◽  
Author(s):  
Doug Smith ◽  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Arctic Sea Ice ◽  
Model Intercomparison ◽  
Scientific Debate ◽  
Model Response ◽  
Arctic Sea ◽  
Intercomparison Project ◽  
Constrained Model ◽  
Arctic Sea Ice Loss

<p>The possibility that Arctic sea ice loss could weaken mid-latitude westerlies and promote more severe cold winters has sparked more than a decade of scientific debate, with support from observations but inconclusive modelling evidence. Here we analyse a large multi-model ensemble of coordinated experiments from the Polar Amplification Model Intercomparison Project and find that the modelled response is proportional to the simulated eddy momentum feedback, and that this is underestimated in all models. Hence, we derive an observationally constrained model response showing a modest weakening of mid-latitude tropospheric and stratospheric winds, an equatorward shift of the Atlantic and Pacific storm tracks, and a negative North Atlantic Oscillation. Although our constrained response is consistent with observed relationships which have weakened recently, we caution that emergent constraints may only provide a lower bound.</p>

AMOC stability and diverging response to Arctic sea ice decline in two climate models

2021 ◽  
pp. 1-47
Author(s):  
Hui Li ◽  
Alexey Fedorov ◽  
Wei Liu
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Horizontal Resolution ◽  
Arctic Sea Ice ◽  
Meridional Overturning Circulation ◽  
Quasi Equilibrium ◽  
Freshwater Transport ◽  
Sea Ice Decline ◽  
Basin Scale ◽  
Arctic Sea

AbstractThis study compares the impacts of Arctic sea ice decline on the Atlantic Meridional Overturning Circulation (AMOC) in two configurations of the Community Earth System Model (CESM) with different horizontal resolution. In a suite of model experiments we impose radiative imbalance at the ice surface, replicating a loss of sea ice cover comparable to the observed during 1979-2014, and find dramatic differences in the AMOC response between the two models. In the lower-resolution configuration, the AMOC weakens by about one third over the first 100 years, approaching a new quasi-equilibrium. By contrast, in the higher-resolution configuration, the AMOC weakens by ~10% during the first 20-30 years followed by a full recovery driven by invigorated deep water formation in the Labrador Sea and adjacent regions. We investigate these differences using a diagnostic AMOC stability indicator, which reflects the AMOC freshwater transport in and out of the basin and hence the strength of the basin-scale salt-advection feedback. This indicator suggests that the AMOC in the lower-resolution model is less stable and more sensitive to surface perturbations, as confirmed by hosing experiments mimicking Arctic freshening due to sea ice decline. Differences between the models’ mean states, including the Atlantic mean surface freshwater fluxes, control the differences in AMOC stability. Our results demonstrate that the AMOC stability indicator is indeed useful for evaluating AMOC sensitivity to perturbations. Finally, we emphasize that, despite the differences in the long-term adjustment, both models simulate a multi-decadal AMOC weakening caused by Arctic sea ice decline, relevant to climate change.

scholarly journals Evaluation of Arctic sea ice thickness simulated by Arctic Ocean Model Intercomparison Project models

2012 ◽  
Vol 117 (C8) ◽  
pp. n/a-n/a ◽  
Author(s):  
Mark Johnson ◽  
Andrey Proshutinsky ◽  
Yevgeny Aksenov ◽  
An T. Nguyen ◽  
Ron Lindsay ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ocean Model ◽  
Arctic Sea Ice ◽  
Ice Thickness ◽  
Model Intercomparison ◽  
Sea Ice Thickness ◽  
Arctic Sea ◽  
Intercomparison Project ◽  
Arctic Sea Ice Thickness

The impact of Arctic sea ice cover on seasonal modulation of the M2 tide

2020 ◽  
Author(s):  
Inger Bij de Vaate ◽  
Amey Vasulkar ◽  
Cornelis Slobbe ◽  
Martin Verlaan
Keyword(s):  
Sea Ice ◽  
Tide Gauge ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Water Levels ◽  
The Arctic ◽  
Data Set ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
The Impact

<p>The impact of Arctic sea ice decline on future global tidal and storm surge extreme water levels is unknown. Regional studies show that the impact can be substantial; causing increased erosion and posing higher risks to fragile Arctic ecosystems in low-lying areas. Since Arctic tides and surges influence global water levels, consequences of Arctic sea ice decline will be noticed across the globe. In the ongoing FAST4Nl project, an Arctic Total Water Level model will be used to quantify this impact. The model will be developed as an extension of the operational Global Tide and Surge Model (GTSM) and includes the effect of sea ice on tides.</p><p>Here we present the results of a study on the seasonal variability of the M<sub>2</sub> tide with respect to differences in sea ice cover. The effect of sea ice on the M<sub>2</sub> amplitude was modelled for minimal and maximal sea ice configurations. In addition, tidal harmonic analysis was performed on a global tide gauge data set, supplemented by SAR altimeter derived water levels from the Arctic region. The high along-track resolution of SAR altimeters (300 m) enables to derive water levels from leads in the sea ice. Here, the retrieved sea surface heights within a given region were stacked, in order to obtain a sufficiently large data set for analysis of the predominantly ice-covered areas. This allowed to gain insight in the seasonal modulation of both local and global tides and directly relate these processes to variations in sea ice.</p>

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